1. Field of the Invention
The present invention relates to a grommet structure of a wire harness having an electric wire covered with a shield member, and to a wire harness to which this grommet structure is applied.
2. Description of the Related Art
When a wire harness is to be laid straddling inside and outside of a passenger room of an automobile, the wire harness is laid through a water-block grommet to prevent water existing outside of the passenger room from entering the inside of the passenger room via the wire harness. FIG. 1 shows an example of such a conventional grommet structure of the wire harness which is disclosed in a Patent brochure, Japanese Patent Application Laid-open No. Hei-11-232948.
As shown in FIG. 1, a wire harness WH includes electric wires W, and a grommet 50 added to the electric wire W. The grommet 50 comprises an electric wire holding portion 52 having an electric wire insertion hole 51 therein, a substantially conical panel crimping portion 53 which is integrally provided on the electric wire holding portion 52, and an inner peripheral holding portion 55 which is disposed on the inner peripheral side of the panel crimping portion 53 through space S. A shield charging chamber 54 is formed in the inner peripheral holding portion 55. The electric wires W are inserted into the insertion hole 51 and in this state, shield material 56 is charged into the shield charging chamber 54, and the charged shield material 56 is solidified to lay grommet 50 in the wire harness WH. The wire harness WH in which the grommet 50 is laid is passed through an electric wire through hole of a vehicle body panel (not shown), and an annular recess 53a of the panel crimping portion 53 is fitted to a peripheral edge of the electric wire through hole.
In the above structure, a water passing between the grommet 50 and the vehicle body panel is blocked by the fitting structure, and water pass between the electric wire W and the grommet 50 is blocked by the charged shield material 56. With this structure, it is possible to reliably block water.
In order to secure the electromagnetic shielding, a wire harness having a braided wire (shield member) covering an outer periphery of the electric wire is used in some cases. Since high voltage (e.g., 42V) is applied to a wire harness used in an electric automobile for example, a wire harness having an electric wire covered with a braided wire is used to prevent adverse influence caused by electromagnetic waves. When the wire harness having such a braided wire is laid in the grommet of the electric wire press fit structure, since water enter from a gap of the braided wire which is press fitted into the electric wire press-fit hole of the grommet, water cannot be blocked reliably. If the above conventional grommet is laid, since the shield material 56 enters the gap of the braided wire, water does not enter from the gap of the braided wire, and water can reliably be blocked.
According to the grommet structure of the conventional wire harness WH, since it is necessary to charge the shield material 56 into the shield charging chamber 54 of the grommet 50, there is a problem that the productivity is inferior.